Hi, ID is not only unique for a layer, it is unique for all the features derived from AbstractBasicFeature (mainly BasicFeature). Note : when you connect to a database in such a way that data is only loaded on demand, the same feature can take successively different ids each time it is reloaded. Some plugins may have there own implementation of Feature and manage id differently.
Michaël Sunburned Surveyor a écrit : >Stefan wrote: "the ID should be unique within one layer..." > >That is what I thought. Thank you for confirming. > >Stefan wrote: "for cloning and copying look in the code!" > >Actually, the getID method is defined in the Feature interface, and is >implemented by BasicFeature. I think this leaves open some room for >problems. Although our interface specifies the basic behavior of the >getID method, it doesn't really specify the details of the mechanism >used to identify Feature objects. Even if I look at the behavior of >copying and cloning in the BasicFeeature implementation, it is >possible that my FeatureCache might have to deal with implementations >that do not use the same behavior. > >I will have to think about this problem some more. Perhaps I am >missing something. > >Thanks for the suggestions. > >The Sunburned Surveyor > > > >On 7/8/07, Stefan Steiniger <[EMAIL PROTECTED]> wrote: > > >>the ID should be unique within one layer.. >> >>for cloning and copying look in the code! >> >>Sunburned Surveyor schrieb: >> >> >>>I'm still chipping away at my FeatureCache. I'm currently working on >>>the class that will write Features to a binary file that uses a >>>shortened format of BOFF. >>>(http://thejumppilotproject.pbwiki.com/Binary+Open+Feature+Format) >>>Part of the format stores a unique numeric identifier for the Feature, >>>which I will also be using in my FeatureCache internally. >>> >>>The BOFF format defines this unique numeric identifier for features as >>>an 8 byte long. The Feature interface provides a getID method that >>>returns an int. This isn't a problem, since I Java will automatically >>>convert the int to a long. >>> >>>However, I need to ask some questions about the getID method so that I >>>don't use it improperly in the guts of the FeatureCache. Is the int >>>returned by the getID method gauranteed to be unique within each >>>FeatureCollection? Can a Layer contain two Features with the same ID? >>>What if a Feature is cloned or copied? >>> >>>Thanks for any information on how the ID mechanism for Features works >>>in JUMP/OpenJUMP. >>> >>>The Sunburned Surveyor >>> >>>------------------------------------------------------------------------- >>>This SF.net email is sponsored by DB2 Express >>>Download DB2 Express C - the FREE version of DB2 express and take >>>control of your XML. No limits. Just data. Click to get it now. >>>http://sourceforge.net/powerbar/db2/ >>>_______________________________________________ >>>Jump-pilot-devel mailing list >>>Jump-pilot-devel@lists.sourceforge.net >>>https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >>> >>> >>> >>> >>------------------------------------------------------------------------- >>This SF.net email is sponsored by DB2 Express >>Download DB2 Express C - the FREE version of DB2 express and take >>control of your XML. No limits. Just data. Click to get it now. >>http://sourceforge.net/powerbar/db2/ >>_______________________________________________ >>Jump-pilot-devel mailing list >>Jump-pilot-devel@lists.sourceforge.net >>https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >> >> >> > >------------------------------------------------------------------------- >This SF.net email is sponsored by DB2 Express >Download DB2 Express C - the FREE version of DB2 express and take >control of your XML. No limits. Just data. Click to get it now. >http://sourceforge.net/powerbar/db2/ >_______________________________________________ >Jump-pilot-devel mailing list >Jump-pilot-devel@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel > > > > ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
